Shaft positioning mechanism



Nov. 4, 1952 J. M. UNK ET AL SHAFT POSITIONING MECHANISM Filed Jan. 28, 1949 DRIVING MEfl/VS PAM/L SHAFT /6 CONT/ML MEI/V5 OVERLOAD 2/ [OUPLM/G 0R CZUTC/l ,Z'nveniims AGE/VT Patented Nov. 4, 1952 2,616,299 sH AF'T POSITIONING MEQHAN'I'SM Jacob Marinus- Unkand Wilhelm-us llambertus V'erv'es't, Ei'ndhoven; Neth'eflahds, ess'ignors to Hartford National Bank and Trust Gom'pany, Hartford; Conn, as trustee? Ap neatidn'ranuery 28, 1949, Serial No. 73,2"7 2" Iii the'Netherlands February 23, 1948 10 Claims.- 1-

For the purposeof accurately"positioning a rotary element, foi instance a tuning element of a radio" transmitter or receiver? it is known td couple this element witha device comprising a shaftwhich is adaptew to be lock'ed in on*e' oi more predetermined: positions/by means of one or more movable p-awlsarranged at the side of the shaft: For this purpose,- the shaft-to be 10 eked, referred tohereinafteras the main shaft,- is' provided with lockiri'g elements} for example discs or rings, each having a profiled: edge. By the" engagement of a pawl with alocking element the main shaft. when z otatin'g'" in one: direction, is locked accuratelyin a position determined by the position of. the locking element relatively to the main shaft";

The pawls which must be movably' arrang'ed i n order that one of them at will m'ay/ co-operate with the'locking element on the main shaft are supported in the known devices by a shaft which is substantially parallel to the main sh'aft a single shaft being adapted t'o sup'port all the'p'awl's or as the" case may" be'each pawl bein asso' elated with asep-arat'e'shafte- In the'first case each of the" pawls is free" to rotate about the single shaft, ini therother 'case thepawls may each be adapted to rotateabout-the: shaft bywhich it is supportedon be secured? to it, it then' being necessary for each of these" shafts: to'be adapted to-rotate- A shaft" serving to support one-or more pawls is referred to" hereinafter aspawl shaft.

In devices as describedabove it is frequently desirable that the mainshaft sh-ou ld rapidly oecupy the desired position. This-cam be realized by' ahigh speed of rotatio'n of the main shaft when moving: to the" new position. There is, however, a limitation in that}: the higher the speed of movement, the heavier is the shock which the pawl, which engages a locking; e1e-- menton the'main'shaft on reaching the new po-'-' sition, has to sustain. Thisshock may exert such a force on'the -pawl and the locking element that damageis unavoidable;

The I invention has f or its' -dbject I to" provide improved construction of a de'vic'e of the kiiid d scribed abovein which provision is made to reducethe force exerted on th'e pe'wr which engages when the movement of the main shaft is locked; Abcording to the invention: a pawl shaft is adapted to move in a direction 'which corre spends-at least-partly with the direction o,f"th"e'- force-- exerted by the main shaft upon Being locked; on thepawl supphrtedby'the"pawlshaft' against thisdirectionthemovement of the pawl 4 sh-aift is- Iim-itedby' stop; the pawl shaft being held by resilience in the extreme position deterifilhd by the said stop. Ohthe main shaft beihg' locked; th'e shock is borne by the pawl and transferred by the latter to its pawl shaft and the support-tor the latter; Thepawl shaft will thus be'moved in apdirec'tion opposite to that of the-force of the 's'pringf which holds the pawl shaft the extremepos-ition determined by the stop: Resilience brakes the movement of the ni ai'I-i shaft. The latter is thus stopped, whereupon -both the pawl-shaft with the pawl and the main shaft with the elements coupled there- With are-resiliently urgedback until the afores ai d stop prevents any further" retractin move ment of-the' pawl shaft; The main shaft is thus eventually locked ina predetermined position which is determined by the locking element which co operates with the" pawl when in engagement and by the extreme position to" be occupied by the pawl shaft.- Dueto the fact that on the pawl coming into action the shock is resiliently borne;.sthati's to'say' due to the fact that the rotary move'ment ofthe main shaft is braked over a finite path, the force exerted on the pawl during this braking!- by the locking element is lowerthan in. the absenceof movement over this braking-path; The improved construction permits" of adjusting the mainshaftat a high rate withoutany fear thatth'e pawls andtheir support will be-damaged and without the need to reinforce the'variousparts subjectedtothe locking forceswa-reinforcement by which the whole of the device would beenlarged.

In: apreferred embodiment of the" device according: to the invention; in which eeich=- pawl is seated on a separate pawl shaft, the pawl shafts which are arranged to surround the main shaft, are"ro-tatably"supported 'i-rr two spaced plates which are arranged at right angles to the main shaft and are rotatably supported: by the main shaft and the system formed by the plates and the pawlshafts i's kept with the use of at least one spring in a directiofi opposite to the di'r'ec tio'nor rotation of" the main shaft in engagemeaewanafixed part; No ew-1 shaft in this eihbddiiherit is" resui nuy supported singly, but rue-mm shaftsare houseditbge ther in a strii'c tiiife f armed by plates*-at -ri'ght angles to the' shaft and adapted tii m'o'v'e about the shaft; the s't ru c hire-being kept initsextremepositioh'byat least one spring. Q

In an alternative preferred embodiment, each 9? t e h a provided with an extension which eedbyt ie p gagaihst"the'sanie fiiied'part of the device and the plates are movable relatively to one another, at least to a limited extent, about the main shaft. The possibility of a relative rotary movement of the plates ensures that both of them invariably take up the extreme positions to be occupied, so that the position of the pawl shafts is undu'biously determined. This is particularly important if great accuracy and reproduceability of the positions in which the main shaft is adapted to be locked is required.

In order that the invention may be more clearly understood and readily carried into effect, it will now be described more fully with reference to the accompanying drawing, in which Fig. 1 is a diagrammatic front view of a device according to the invention, and

Fig. 2 is a diagrammatic side view of this device.

Surrounding a shaft I required to be locked,

which is adapted to rotate in the direction indi- -2 cated by the arrow P, are arranged parallel thereto a plurality of pawl shafts 2in the embodiment shown twelveeach of which supports a pawl 3, only two sets of the pawl shafts and pawls being shown. Each pawl shaft 2 is parallel to Y the main shaft I and is rotatably supported in an aperture 4 provided in either of two spaced identical plates 5 which are at right angles to the shaft I. The two plates 5are adapted to rotate about the shaft I and are supported thereby. The apertures 4 in these plates are arranged in a circle concentric to the shaft I and are evenly distributed about this circle.

Seated on the shaft I in known manner are a number of disc-shaped locking elements 6, each having a recess 1 at its edge. By movement of the corresponding pawl shaft the edge of each disc 6 is enabled to engage one of the pawls 3. For this purpose, the pawls 3 exhibit a relative shift in the direction of the shaft I. of the discs 6 is shown, viz. that which the pawl 3 shown in Figure 1 is adapted to engage. However, two of the discs 6 are shown in Figure 2 in order to illustrate their relationship along the shaft I.

Each plate 5 is provided at its edge with an extension 8 which exhibits an aperture 9 and with a second extension In spaced away from the first. The apertures 9 of the plates receive the ends of a stressed wire spring I I by which the two plates i=1 are linked. The centre of the spring II exerts a force on a projecting lug I2, which is secured to a bar I3, which passes between the extensions 8 and II of the plates 5. As a result of the spring I I being stressed the two plates 5 are subjected to a couple of forces opposite to the direction of rotation of the shaft I. However, movement of the plates as a result of this couple of forces is prevented by the extensions IIl engaging the bar I3 at A. The edge of the lug I2 which engages the spring II, does not extend concentrically to the bar I3. The bar I3 is held by the frame plates H! of the device, one of them being shown in part in Fig. 1. The bar I3 is adapted to rotate about its axis and the lug I2 is carried along therewith, so that the spring I I may be stressed to a greater or smaller extent. The space between the plates 5 is sealed by a sleeve I5 which engages the edge of the plates. The sleeve I5 shields the pawls arranged about the shaft I and also keeps the plates 5 spaced apart. The edge of the sleeve comprises recesses, from which the extensions 8, It, I6 and I! of the plates project. The recesses are chosen to be of such ample size in a tangential direction that the two plates 5 can be rotated Only one relative to one another. The movability of the plates relative to one another thus realized results in that the extension I0 of each plate is constantly urged against the bar I3, so that the position of the pawl shafts is determined in an undubious manner. The plates 5 are kept linked up by the flexible wire linkages I8, which are taken through apertures provided in the extensions I0, I6 and I1.

The device described operates as follows. For locking the shaft I rotating in the direction P with the use of a pawl 3, the end of this pawl is kept in engagement with the edge of the disc 6 arranged under the pawl by rotation of the shaft 2 on which the pawl is seated. The particular pawl shaft 2 to be rotated may be selectively actuated by pawl shaft control means 22. Such means shown diagrammatically in Figure 2 of the drawings may be of the type shown in U. S. Patent No. 2,530,795 issued November 21, 1950, to J. M. Unk, one of the co-inventors in the present application. On the recess I reaching the end of the pawl 3, this pawl snaps in and further relative rotation between the shaft I and the pawl 3, and hence also between the shaft I and the system formed by the plates 5 and supporting all the pawl shafts is prevented. However, the shaft I, together with the elements coupled therewith has some kinetic energy and by the intermediary of the pawl 3 this causes the plates 5 with the associated pawl shafts to perform a movement in the direction of rotation of the shaft I. However, this movement is counteracted by the spring II, which is stressed still further by this movement. Consequently, the spring locks the moving part of the device comprising the shaft I and the structure formed by the plates 5 and coupled with the shaft by the pawl 3 and then urges this part backwards until the extensions III again engage the bar I3.

When the movement of the shaft I is being braked consequent upon the pawl 3 snapping in, the edge of the recess 7 exerts on this pawl a force which, since braking is effected against the couple of forces exerted by the spring I I through a given path, is considerably smaller than the force which the pawl would have to bear, if the structure formed by the plates 5 had not been rotatable and the braking path were determined solely by resilient deformation of the pawl and its support.

The spring I I exhibits such rigidity and such a bias that the braked part of the device, and hence also the shaft I, is returned to the position in which the extensions I0 engage the bar I3, a position which consequently is fully determined and reproduceable. The bias of the spring I I depends on whether or not the shaft I remains subjected to a couple of driving forces. The shaft I may, for example, be driven by a driving shaft I' connected to the shaft I through a clutch 20 which on exceeding a given countercouple is released, a driving couple remaining continuously exerted, on the shaft by the use of springs in the said clutch. The driving shaft I' may be driven by driving means 2| of conventional design, such as an electric motor, for example. A clutch or overload coupling of such type construction and which may be utilized for the clutch shown diagrammatically in Fig. 2 of the drawings, is shown in copending application Serial No. 51,604 filed September 28, 1948, for a Device for Coupling a, Driving Shaft with a Driven Shaft and Comprising a Coupling Which is Disengaged Upon Overloading, by J. M. Unk, one of the co-inventors of the present application. In this case, for returningthe b-ra-kedpart- 1 the device; the-spring H must be capable of overcoming the couple of driving force which" still acts on the shaft. The biasof the spring H may, as described'abovabe adjusted by' rotation of thebar I 3 and the lug l2 secured thereto, 50- that in-{accordance with the direction of rotation of the bar, the spring is bent to a greater orless extentand thus a greater or less great counter-couple is obtained. Thus, the resilience of the spring-may be adapted to the nature of'the drive of the-"shaft; l 't'o be locked.

What weclaim is 1. Shaft positioning mechanism comprising a control shaft to be positioned, a pluralityz-of1 stop members mounted: on said control shaft, a. p111?" ral'i ty of rotatable stoppawl's each adapted effgage selectively with agc-orrespondingone of, said stop members, a separate pawl shaft supportmg each of said pawls, supporting means forsaid pawl shafts, "said supporting means pennitti'ng rotative movement of said pawli shafts study about said control shaft upon engagement of any pawls with its corresponding member on said control shaft, resilient means for restrainingflsuch bodily rotative movement Qfsaid pawl shafts about said control shaftand" stcp means, for

checking said pawl shafts, in; extrem position under influence of said resilient means 2. Shaft positioning mechanism comprising a control shaft, a plurality of stops members mounted onsaid control" shafl'l',,. a,p11irality of rotatable pawls, each mounted 'ona different one of a plurality of pawlshaftsarranged in parallel relation with'said control shaft, said pawls being adapted to engage with a corresponding stop member on said control shaft for arrestingsaid control shaft predetermined positions, supporting means for said pawl shafts, said supporting means permitting rotative movement of said pawl shafts in a body about said control shaft upon engagement of one of said pawls with its corresponding stop member on said control shaft, resilient means restraining such movement of such pawl shafts and stop means for checking said pawl shafts in extreme position under influence of said resilient means.

3. Shaft positioning mechanism comprising a control shaft, a plurality of stop members mounted on said control shaft, a plurality of rotatable pawls, each mounted on a different one of a plurality of pawl shafts arranged in parallel relation with said control shaft, said pawls being adapted to engage with a corresponding stop member on said control shaft for arresting said control shaft in predetermined positions, com- 7 mon supporting means for said pawl shafts, said common supporting means permitting rotative movement of all of said pawl shafts in a body about said control shaft upon engagement of one of said pawls with its corresponding stop member on said control shaft, resilient means restraining such movement of all of said pawl shafts and stop means for checkin all of said pawl shafts in extreme position under influence of said resilient means.

4. Shaft positioning mechanism comprising a. control shaft, a plurality of stop members mounted on said control shaft, a plurality of rotatable pawls, each mounted on a different one of a plurality of pawl shafts arranged in parallel relation with said control shaft, said pawls being adapted to engage with a corresponding stop member on said control shaft for arresting said control shaft in predetermined positions, supporting means for said pawl shafts; said supporting-v means comprising two spaced plates which are at right angles to said control shaft and rotatably supported thereby, such rotation occurring upon engagement of one of said pawls with its corresponding stopmember on said control shaft, resiiient means restraining such rotation of said two plates and stop means for checking said two plates extreme position under influence of said resilient means.-

5i. Shaft positioning mechanism comprising a contror shaft, a plurality of stop members mounted on said-control shaft, a plurality of rotatable pawls, each mounted on a different oneof' a plurality of pawl shafts arranged inparallel relation with-said control shaft, said pawls being adapted to engage witha corresponding stop member on: said control shaft for arresting said control shaft in predetermined positions, supporting means for: said pawl shafts, said" sup= porting -means comprising two spaced plates: which are at right angles to said control shaft and rotatably supported thereby, such rotation occurring uponengagementof one of said pawlswith itsicorresponding stop member on said control shaft, resilient means restrainingsuch rotation of said two plates each of said plates-having an extension thereon, means interconnecting said plates for' permitting" limited movement relative to each other, and stop means engageablewbyzsaid extensionsforchecking said two plates in extremezposition under-influence of saidresilient; means.

6. Shaft-1 position-ing mechanism comprising a control shaft; a plurality of" stop members mounted on said control shaft, a plurality of rotatable pawls, each mounted on a different one ofiaplurality or pawl shafts" arrangedin parallel relation with said control shaft, said pawls being-adapted to engage with a corresponding stop member on said control shaft for arresting said control shaft in predetermined positions, supporting means for said pawl shafts, said supporting means comprising two spaced plates which are at right angles to said control shaft and rotatably supported thereby, such rotation occurring upon engagement of one of said pawls with its corresponding stop member on said control shaft, resilient means restraining such rotation of said two plates, means for adjusting the strength of the restraining effect of said resilient means, each of said plates having an extension thereon, means interconnecting said plates for permitting limited movement relative to each other, and stop means engageable by said extensions for checking said two plates in extreme position under influence of said resilient means.

7. Shaft positioning mechanism comprising a control shaft, a plurality of stop members mounted on said control shaft, a plurality of rotatable pawls, each mounted on a different one of a plurality of pawl shafts arranged in parallel relation with said control shaft, said pawls being adapted to engage with a corresponding stop member on said control shaft for arresting said control shaft in predetermined positions, supporting means for said pawl shafts, said supporting means comprising two spaced plates which are at right angles to said control shaft and rotatably supported thereby, such rotation occurring upon engagement of one of said pawls with its corresponding stop member on said control shaft, resilient means restraining such rotation of said two places, means for adjusting the strength of the restraining effect of said resilient means, said adjusting means comprising a movable lug having a camming surface cooperating with said resilient means, each of said plates having an extension thereon, means interconnecting said plates for permitting limited movement relative to each other, and stop means engageable by said extensions for checking said two plates in extreme position under influence of said resilient means.

8. Shaft positioning mechanism comprising a control shaft, a plurality of stop members mounted on said control shaft, a plurality of rotatable pawls, each mounted on a different one of a plurality of pawl shafts arranged in parallel relation with said control shaft, said pawls being adapted to engage with a corresponding stop member on said control shaft for arresting said control shaft in predetermined positions, supporting means for said pawl shafts, said supporting means comprising two spaced plates which are at right angles to said control shaft and rotatably supported thereby, such rotation occurring upon engagement of one of said pawls with its corresponding stop member on said control shaft, resilient means restraining such totation of said two plates, said resilient means comprising a flexible element which extends in the direction of said control shaft and is mounted on said two plates, means for adjusting the strength of the restraining efiect of said resilient means, said adjusting means comprising a movable lug having a camming surface cooperating with said resilient means, said movable lug being mounted on means which are stationary relative to said plates, each of said plates having an extension thereon, means interconnecting said plates for permitting limited movement relative to each other, and stop means for checking said pawl shafts in extreme position under L0 influence of said resilient means.

9. A device comprising a rotatable main shaft, a rotatable pawl shaft arranged beside said main shaft and substantially parallel thereto, a pawl mounted on said pawl shaft for movement therewith, pawl receiving means mounted on said main shaft for movement therewith and positioned in operative relationship with respect to said movable pawl, movable mounting means for said pawl shaft, means for resiliently stopping movement of said mounting means in one direction of rotation of said main shaft, and other means for positively stopping movement of said mounting means in the other direction of rotation of said main shaft.

10. A device comprising a rotatable main shaft, a plurality of rotatable pawl shafts arranged around said main shaft and substantially parallel thereto, a pawl mounted on each of said pawl shafts for movement therewith, a plurality of pawl receiving means mounted on said main shaft for movement therewith and each positioned in operative relationship with respect to one of said movable pawls, mounting means for said pawl shaft rotatively mounted on said main shaft, means for resiliently stopping movement of said mounting means in one direction of rotation of said main shaft, and other means for positively stopping movement of said mounting means in the other direction of rotation of said main shaft.

The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date May Dec. 25, 1945 Number 

